1. 2.1 Writing Equations

2. You evaluated and simplified algebraic expressions.
Translate sentences into equations.
Translate equations into sentences.
Then/Now

3. formula
Vocabulary

4. A. Translate this sentence into an equation.
Translate Sentences into Equations
A. Translate this sentence into an equation.
A number b divided by three is equal to six less than c.
b divided by three is equal to six less than c.
= c – 6
Answer:
Example 1

5. B. Translate this sentence into an equation.
Translate Sentences into Equations
B. Translate this sentence into an equation.
Fifteen more than z times six is y times two minus eleven.
Fifteen more than z times six is y times two minus eleven.
z × = y × –
Answer: The equation is z = 2y – 11.
Example 1

6. A. Translate this sentence into an equation
A. Translate this sentence into an equation. A number c multiplied by six is equal to two more than d.
A. 6c = d + 2
B. 2c = d + 6
C. c = d + 2
D. c = 6(d + 2)
Example 1

7. B. Translate this sentence into an equation
B. Translate this sentence into an equation. Three less than a number a divided by four is seven more than 3 times b. A. B. C. D.
Example 1

8. Use the Four-Step Problem-Solving Plan
JELLY BEANS A jelly bean manufacturer produces 1,250,000 jelly beans per hour. How many hours does it take them to produce 10,000,000 jelly beans?
Understand You know that 1,250,000 jelly beans are produced each hour. You want to know how many hours it will take to produce 10,000,000 jelly beans.
Plan Write an equation to represent the situation. Let h represent the number of hours needed to produce the jelly beans.
Example 2

9. Find h mentally by asking, “What number times 125 equals 1000?” h = 8
Use the Four-Step Problem-Solving Plan
1,250, times hours equals 10,000,000.
1,2500, × h = ,000,000
Solve 1,250,000h = 10,000,000
Find h mentally by asking, “What number times 125 equals 1000?”
h = 8
Answer: It will take 8 hours to produce 10,000,000 jellybeans.
Check If 1,250,000 jelly beans are produced in one hour, then 1,250,000 x 8 or 10,000,000 jelly beans are produced in 8 hours. The answer makes sense.
Example 2

10. A person at the KeyTronic World Invitational Type-Off typed 148 words per minute. How many minutes would it take to type 3552 words?
A. 148 minutes
B. 30 minutes
C minutes
D. 24 minutes
Example 2

11. Words Perimeter equals four times the length of a side.
Write a Formula
GEOMETRY Translate the sentence into a formula. The perimeter of a square equals four times the length of a side.
Words Perimeter equals four times the length of a side.
Variables Let P = perimeter and s = length of a side.
Perimeter equals four times the length of a side.
Formula P = s
Answer: The formula is P = 4s.
Example 3

12. Translate the sentence into a formula
Translate the sentence into a formula. The area of a circle equals the product of  and the square of the radius r.
A. A =  + r2
B. A = r2
C. A = 2r
D. A = 2r + 
Example 3

13. Group Work on Board Skills practice #1-10